Compressors are used in various compression systems, such as refrigeration systems, to compress gas, such as Freon, ammonia, natural gas, or the like. One type of compressor is a single screw gas compressor, which is generally comprised of three basic components that rotate and complete the work of the compression process. These components include a single cylindrical main screw rotor with helical grooves separated by a plurality of identical lands, and two gate rotors (also known as star or star-shaped rotors), with each gate rotor having a plurality of teeth that extend radially outwardly from its center. The rotational axes of the gate rotors are parallel to each other and mutually perpendicular to the axis of the main screw rotor. This type of compressor employs a housing in which the helical grooves of the main rotor mesh with the teeth of the gate rotors on opposite sides of the main rotor to define gas compression chambers. The housing is provided with two gas suction ports, typically one near each gate rotor, for inputting the gas and with two gas discharge channels, again typically one near each gate rotor, for entry and exit of the gas to the gas compression chambers. It is known to provide two dual slide valve assemblies on the housing, with one assembly typically positioned near each gate rotor, with each slide valve assembly comprising a suction valve (also referred to as a “capacity slide valve”) and a discharge slide valve (also referred to as a “volume slide valve”) for controlling an associated intake channel and an associated discharge channel, respectively. In operation, an electric motor imparts rotary motion through a driveshaft to the compressor's main rotor, which in turn rotates the two intermeshed gate rotors, and gas is compressed in the gas compression chambers.
Known main rotors comprise identical lands consisting of a single wrap angle. More particularly, the single wrap angle corresponds to, or otherwise describes, a starting point on the outer diameter of a respective one of the lands of the main rotor as the point travels, during rotation of the rotor about its rotational axis, from the starting point on the respective land of the rotor to a final point on the respective land of the rotor.
It has been determined that an increase in the wrap angle of the main rotor (i.e., particularly the single wrap angle of the respective identical lands of the main rotor) results in an increase in compressor output. In general, for a given main rotor diameter, for example, an outside diameter corresponding to outside surfaces of the lands, and a given gaterotor diameter, the wrap angle of any given main rotor must remain below 180 degrees so as to permit mounting of the gaterotor with respect to the main rotor when the main rotor is already positioned in the housing of the compressor, as is typically the case during assembly of the compressor.
It would be advantageous to provide a single screw compressor with high output that overcomes the problems associated with the above.